Old Car ('76 450SL), New Owner, Few Questions. Please Help

[rzrob]

Hello,

I own a '03 E class, but just purchased a '76 450SL from a coworker. Real pretty car. It's not perfect though. I was hoping some of you with more experience could help me figure out a few things:

Headlights - One side is out, but when I hit the highbeams all 4 go on. It seems to be inconsistent. I'm suspicious of the highbeam switch (turnsignal, wiper etc.). Any ideas?

Turn signal switch - doesn't stay locked either. Is this fixable, or should I just replace it? If it's related to the headlight not working, maybe I'm best off replacing. Any clues on removing it?

Parts - I need a good place to get little parts like turn signal switch, taillight lenses and front bumper and floor mats and dash pad. Any good sources for best price (Internet hopefully)?

Steering - is loose. Is there something that wears that I can replace?

Tires - Has Yoko Aegis 205/70r 14. Anybody ever put a meatier tire on the stock rims? I'm wondering about a 60, like a 225 or 235. Will this look too beefy - or even fit? I just want a sportier look.

Any help with these items greatly appreciated. I'm reasonably mechanically inclined and live in Southern California.

Rob